Lymphoplasmacytic lymphoma is a low-grade B-cell lymphoma with plasmacytic differentiation, almost always IgM + (rarely IgA + or IgG +) and associated with bone marrow involvement, typically associated with an IgM M component, and almost always with an underlying MYD88 p.L265P. This evidence concerns the gene CD40LG and lymphoplasmacytic lymphoma.